VPS默认DNS失效导致Nginx反代失败，提示upstream xxxx且主机此时无法ping通其他域名，此时需指定DNS服务器。
由于Debian的/etc/resolv.conf默认是软链接，需要删除重建，否则重启会失效。
1 2 3 4 5 sudo cp /etc/resolv.conf /etc/resolv.conf1 sudo rm /etc/resolv.conf sudo mv /etc/resolv.conf1 /etc/resolv.conf
重建好之后，再次确认文件权限配置，否则按以下情况处理
1 2 sudo chown root:root /etc/resolv.conf sudo chmod 644 /etc/resolv.conf
修改/etc/resov.conf文件内容，例如
1 2 3 4 5 6 7 8 # Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8) # DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN nameserver 119.29.29.29 nameserver 180.76.76.76 nameserver 101.6.6.6 nameserver 240c::6666 nameserver 240c::6644 nameserver 2001:da8::666
为确保万无一失，可以检查/etc/network/interfaces中的DNS服务器配置是否正确，例如
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 # This file describes the network interfaces available on your system # and how to activate them. For more information, see interfaces(5). source /etc/network/interfaces.d/* # The loopback network interface auto lo iface lo inet loopback # The primary network interface allow-hotplug eth0 iface eth0 inet static address 11.111.111.111 netmask 255.255.254.0 network 11.11.111.0 broadcast 11.111.111.255 gateway 11.111.111.1 # dns-* options are implemented by the resolvconf package, if installed dns-nameservers 119.29.29.29 180.76.76.76 101.6.6.6 77.88.8.8 1.1.1.1 8.8.8.8 dns-search kvm.233 iface eth0 inet6 static address 2400:c700:1::6:ef netmask 64 gateway 2400:c700:1::1 dns-nameservers 2001:da8::666 2001:4860:4860::8844 2001:4860:4860::8888 209.244.0.3 2a00:b700::220 2a00:b700:1::220
